Final answer:
The potential energy of a wooden log burning in a fireplace is transformed into kinetic energy of heat and light, aligning with the law of conservation of mass. The glowing of embers represents blackbody radiation. The photoelectric effect shows light's dual nature, affecting how it interacts with matter at a quantum level.
Step-by-step explanation:
The best description of the flow of energy when a wooden log is placed in a fireplace and burned until only ashes remain is that the potential energy of the wooden log was converted into the kinetic energy of heat and light. During combustion, the log reacts with oxygen, releasing energy in the form of heat and light, and producing ash and gases such as carbon dioxide and water vapor as byproducts. The ashes weigh less because most of the mass of the wood is converted into these gases and released into the atmosphere. This process aligns with the law of conservation of mass, which states that mass cannot be created or destroyed in a chemical reaction.
In terms of energy transfer, when the wooden log burns for an extended period, it eventually turns into hot embers that glow a bright orange and whitish-yellow. This glow is a demonstration of blackbody radiation, where the embers emit light at different wavelengths due to their high temperature. The energy transfer occurs from the potential chemical energy stored in the bonds of the wood to thermal energy, which we observe as heat.
Regarding the photoelectric effect and blackbody radiation, the quantum explanation indicates that light has both wave and particle characteristics. When light of a sufficient energy level (or of a wavelength equal to or shorter than a specific threshold) shines on a metal surface, it can eject electrons from the metal. This property is essential for understanding how light interacts with matter on a quantum level.